In order to create a child org, while on the organizations screen (the same one that we went over when editing your organization's name and logo)
From there, click on the red “+ Add Child Organization”
Once you click on that button, it will appear as if the name has gone blank, this is because you are now creating the child org.
Similar to setting up the parent organization, you will need to name the child org and make sure to click the red "Create Child Organization button" in order to save it.
You won't have to add a new logo (but if you would like to you can) because the logo will be the same as the parent organization.
To change the child orgs logo you will have to click on the Change Organizations Button and navigate to the Child Org.